The demand on vehicle brake systems having brake boosters is to optimally perform a braking operation initiated by the driver even if the driver's behavior is not always commensurate with the respective situation involved. To this end, electromagnetically actuated control means for additional are were provided which were activated in response to the actuation dynamics of the brake pedal (cf. the previously filed and post-published German patent applications P 42 17 409 and P 43 09 850 of the applicant).
In the case of an emergency braking, when the braking operation is enhanced by a brake booster, the boosting operation has been increased to an extent as allowed by the pressure differential in the individual chambers of the brake booster. The actuation velocity of the brake pedal was used as the triggering criterion. As soon as a given threshold value of the actuation velocity was surpassed, the maximally possible amplification f the brake boosting operation was initiated. Although this operation results in a considerably shortened brake path, the driver is deprived of the control of the braking operation in that a once initiated full braking proceeds entirely automatically, in other words the driver is no longer in a position to intervene in the braking operation. It is however desirable to stop full braking or emergency braking operations by an intervention on the part of the driver, for instance when the danger does not exist anymore.
In order to control the process of braking initiated by the driver more thoroughly by an electronic control device (ABS) it is very advantageous to have an indication on the dynamics of the braking, i.e. with which velocity per time unit and with which force (of the time unit) the brake pedal is operated by a driver. Indications on these characteristics are very helpful to further optimise the course of a braking process, since the electronic control device can more acutely and more efficiently activate the automatic braking.
Based on the above, the problem underlying the present invention is to provide an apparatus by which a driver-initiated sudden stopping of an emergency braking operation is determined safely and free of interferences and which allows for a control of the braking process to achieve a shorter braking path.
For solving said problem, the afore named apparatus has been further developed by the features of the appended claims.
Further characteristics and advantages entailed by the intention will be described in greater detail in the following description of embodiments of the invention, with reference to the enclosed drawings.